Thermocouple safety pilot switch



Jan. 4, 1949. L. A. MArsoN 2,458,014

THERMOCOUPLE SAFETY PILOT SWITCH l piled my 15. 1944 Patented Jan. 4, 1949 UNITEDv STATES PATENT FFICE THEBMOCOUPLE SAFETY PILOT SWITCH Leroy A. Mama, ramt me, nl., mum u Milwaukee Gal Specialty Company, Milwaukee, ---Wil., a corporation of Wisconsin Application Ma! 15, 1944, Serial No. 535,575

(Ci. 20o-ill 7) l 9 Claims.

This invention relates, in general, to an electric switch, and has particular relation to a thermocouple safety pilot switch.

The device which I shall describe hereinafter in connection with the drawing is particularly adapted for use with a thermocouple safety control device having an electromagnet connected in circuit with a thermoelectric generator and provided with an armature which is held attracted so long as the thermoelectric generator is heated, for example. by a pilot light for a main burner, and moves to retracted position when the pilot light is extinguished.

One of the main objects of the present invention is to provide an improved form of switch having switch operating means adapted to be pressed to move the armature to attracted position without closing the switch, and, thus, without estab.- lishing a supply of fuel for the main burner; the closing of my improved form of switch requiring not only release of the switch operating means, but., also, that the armature be held in attracted position by energization of the electromagnet by the heat, for example, of the pilot flame on the thermocouple.

Another object of the linvention is to provide, as a part of the switch operating means, a plunger which has movement in opposite directions and forms an insulating enclosure for the switch contacts.

Another object of the invention is to provide. in conjunction with the plunger having movement in opposite directions. a pin having sliding movement in the plunger, and switch contacts which are moved into and out of engagement by relative movement between the plunger and the pin.

Another object of the invention is to provide a device of the class described in which the position of the operating button indicates whether the switch isopen or closed.

Another object oi the invention is to eliminate the necessity for resilient or spring contact carrying members; also the necessity for pivotal or swinging movement either in the armature carrying member or in the switch parts.

Another object of the invention is to provide a device of the class described in which the armature, the armature carrying parts, and the parts which carry and control the switch and move the armature to attracted position are all positioned coaxially and operated by rectilinear movement.

Another object of the invention is to provide a device of the character described which is adapted for installation with various types of burner and 2 furnace constructions, and may be mounted for use in any desired position.

Further objects and advantages of the invention will be apparent from the following detailed E description, taken in connection with the accompanying drawing,

In the drawing:

Figure 1 is a schematic view showing one application of a switch embodying the present invention;

Figure 2 is an elevational view of the switch E shown in Figure 1;

Figure 3 is a longitudinal sectional view taken on the line 3--3 of Figure 2;

Figure 4 is a longitudinal sectional view, similar to Figure 3, with the armature in attracted position and the switch closed; and

Figure 5 is a fragmentary longitudinal section taken on the line 5 5 of Figure 4.

In Figure 1 of the drawing, a gas or other fuel burner of any suitable or preferred type is illustrated at I0. The burner l0 may be the burner of a` room or space heater, water heater, floor furnace, gas range, or any other burner. A gas or fuel supply pipe Il leads to the burner I0 for the delivery of gas or other fuel theretofor example, through a mixing chamber l2 to which air is admitted in the usual way, as well understood in the art.

An electroresponsive valve I3, such as a, solenoid or motor valve, is interposed in the fuel supply pipe Il. The valve i3 is shown as comprising a valve body I4 and a hood I5 having any suitable power operated valve actuating means therein. A step-down transformer I8 supplies power for the operation of the valve I3. This transformer comprises a line voltage primary I1 and a low volt' age secondary i8. The .fprimary I1 is connected to line wires I8 leading to any suitable source of current or power (not shown). The valve actuating means for the valve Il, the switch of the present invention. which is designated in its entirety at 2li, and a thermostat, such as a room thermostat 2|, are shown connected in series circuit relation in the secondary circuit 22.

For purposes of the present disclosure it may be assumed that the valve il is of a character to be actuated to open position by closing of the circuit 22, and to be held in open position to supply fuel to the burner iii as long as the circuit 22 is closed. The valve i3 may have spring means or other suitable means for actuating the valve to closed position to shut of! the supply of fuel to the burner i! when the circuit 22 is opened or otherwise disabled.

A pilotl burner 2l is placed in juxtaposition to the maid burner i8 and provides a pilot light or flame 24 for lighting the main burner. A pipe 28, connected to the fuel supply pipe I| anterior of the valve I8, or otherwise as desired, supplies fuel for the pilot burner 28.

'i'ne switcn zu has a generally U-shaped supporting bracket 28.` The U-sh'aped magnet frame 2'i is secured to a terminal bushing 28, for example, in the manner more fully disclosed in Clarence Wantz U. S. Patent No. 2,318,823, issued May 11, 1943. The coil 28 of the electromagnet is wound around the legs of the magnet frame 21. The bushing 28, the shank of which extends through an opening in the adjacent end flange 88 of the bracket 28, is shown as externally threaded for threaded engagement with a nut 8l by means of which the bushing 28 is clamped to the flange 88. A sealing gasket 32 is preferably placed between the head or flange at the inner end of the bushing and the flange 88.

A thermocouple, indicated at 88. is placed in position so that the hot Junction 88 thereof will be heated by the pilot flame 24 as long as the pilot flame is burning. While the thermocouple and leads therefor are shown as similar to the thermocouple and leads more fully disclosed in Oscar J. Leins Patent No. 2,126,564, issued August 9, 1938, it is to be understood that the thermocouple and its leads may be of any other suitable selected for illustration comprises an outer tubular metallic thermocouple element and an inner metallic thermocouple element of different thermoelectric characteristics. The thermocouple elements are joined to form the hot junction 88.

An outer tubular lead conductor 81 is connected to the outer thermocouple element, for example, through a sleeve 88. The inner lead conductor 88, enclosed by and insulated from the outer tubular lead conductor 81, is connected to the inner thermocouple element.

A quick detachable or removable connection is preferably provided between the electromagnet and the ends of the leads 81 and 88 opposite the ends which are connected to the thermocouple element. The inner lead 88 has a connector cone 48 which seats in the correspondingly recessed outer end of the terminal tip 4I and is clamped in contact therewith by a connector sleeve 42 which screws into the outer end of the bushing 28. The adjacent end oi the outer tubu- .lar conductor 31 is connected in circuit with one 48 preferably formed of insulating material, such as a plastic or synthetic resin. The base of the housing 48 is flanged at 48 and secured by screws 41 to the flange 88 of the bracket 28. The armature 48, also enclosed within the housing 48, is carried on the inner end of an armature stem 48 which extends out through the adjacent end of the housing for sliding movement, for example, in a metal insert 88.

The opening through which th'e stem 48 extends is sealed by suitable packing 8| held in place by a cup-shaped spring seat member' 82. An abutment member 82 has its shank screwed into the outer end of the stem 48, thus detachably securing the abutment member to this stem. A coil spring 84, interposed between the spring seat member B2 and a spring seating disc 88, moves the armature 48 to retracted position when it is .released from the electromagnet.

Secured by screws 88 to the bracket or support 28 is a body member 88 preferably formed of insulating material, such as a plastic or synthetic resin. A plunger 8i, also preferably formed of insulating material such as a plastic or synthetic resin, has rectilinear sliding movement in opposite directions in a bore 82 in the body member 88. A pin 88, preferably formed of insulating material, has sliding movement in the plunger 8|. The pin 82, plunger 8i, armature 48, and stem 48 are all coaxial.

The plunger 8i is recessed to receive and enclose the switch which comprises a pair of contacts 84, carried by the plunger 8|, and a bridging contact disc 88 on the pin 88. The contacts 84 have terminals which extend out along the opposite longitudinal edges of the arcuate portion 88 oi' the body member 88. This arcuate portion 88 of the body member partially embraces the spring 84 and adjacent parts and, with the bracket 28, provides protection for these parts. The terminais i'or the contacts 84 are connected by flexible conductors 81 to metallic connector pieces 88 secured to the body member 88 by screws 88, which screws are also adapted to clamp the adjacent ends of the conductors 81 to the connector pieces 88. The conductors, which form a part of the circuit 22. are clamped to the respective connector pieces 88 by screws 18.

The open end of the plunger 8| is closed by an end member 1|, which is also preferably formed of insulating materialsuch as a plastic or synthetic resin. The plunger 8| and end member 1| move as a unit in opposite directions when the device is assembled as shown in the drawing, but upon removal of the body member 88 from the bracket 28 and removal of the plunger 8| from the body member the end member 1| may be removed from the plunger for access to the switch contacts. The end member 1| has an integral button 12 which extends out through an opening in the adjacent flange 88 of the bracket 28.

The pin 88 has, at its inner end, an enlarged head 14 which provides an abutment 18 which cooperates with the plunger 8|, so that when the plunger is moved to the right from the position shown in Figure 3 the pin 88 will move as a unit with the plunger, and, by its cooperation with the abutment member 88, moves the armature 48 to attracted position. The headed end of the pin 88 is preferably rounded, as shown, to seat in a recess ir; the cooperating end oi' the abutment member 8 A spring 88, coiled about the reduced end oi' the pin 88 and interposed between the bridging contact 88, which is loose on the pin, and the end member 1|, acts, upon` removing the linger from the button 12, when the movement of the armature 48 to attracted position is complete and the armature 48 is held in attracted position by the electromagnet, to move the plunger 8| to the left relative to the pin 83, from the position shown in Figure 3 to the position shown in Figure 4. This engages the contacts 84 with the bridging contact disc 88. A spring 8|, which is weaker than the spring 88, is coiled about the end member 1l and interposed between the base of the end member and the flange 38'. The spring holds the plunger 8| and button in place and against dropping, for

marked portion 12' of the button is concealed within the end of the body part 60 and the adjacent fiange 30', as shown. in Figure 4. When the armature is in retracted position and the switch is open, the band oncolored or marked portion 12 is exposed beyond the end oi' the body part 60 and adjacent flange 30.k The presence or absence of the colored or marked portion 12' of the button beyond the end of the body part 60 and flange 30' thus enables the operator to determine at a glance Whether the switch is open or closed.

To start the operation of the system .shown in the drawing, the'following sequence is followed:-

The plunger 6I is pressed inwardly, for example, from the position shown in Figure 3, by engaging the button 12 with the hand or finger and pressing the same. The plunger 6I, by its engagement with the abutment 15 on the pin 63, moves the pin 63 as a unit .with the plunger and with the contacts 64 out of engagement with the contact 65. The pin 63, in its inward movement and byits engagement with the cooperating headed end 53 of the armature stem 43, moves the armature 48 by rectilinear movement from its retracted position, shown in Figure 3, to its attracted position, shown in Figure 4.

Upon ignition of the pilot burner 23, the pilot flame 24, by heating the hot junction 36 of the thermocouple 35, energizes the electromagnet suillciently to hold the armature 48 in attracted position. When the button 12 is released with the armature 48 held in attracted position by the electromagnet, the spring 80 moves the plunger 8| to the left, as shown in the drawing, relative to the pin 63, and from engagement with the abutment 15 on the pin 63 to the position shown in Figure 4. This movement of' the plunger 6| relative to the pin 63 moves the contacts 64 into engagement with the bridging contact 65 to 'close the circuit 22 at the switch 20. Assuming that the circuit is also closed at the thermostat 2|, the valve I3 is opened by the completion of the circuit 22 for the supply of fuel to the main burner III which is then ignited by the pilot flame.

From the foregoing it will be apparent that the switch closes the circuit 22 not by the inward movement of the button 12 or by the armavture resetting operation, but only if and after the armature 48 is held in attracted position by the electromagnet and the button 12 is released.

The closing of the circuit 22 and opening of the valve I4 for thesupply of fuel to the main burner is thus prevented except when the pilot ame is ignited so that it will ignite the fuel which is delivered to the main burner. If the heat of the pilot flame on the thermo couple has not generated sumcient E. M. F. to hold the armature in attracted position, the spring 54 will return the armature 48 to retracted position and the plunger. 6I and' pin 63 to the positions show-n in `Figure 3, the switch remaining 'open and the valvek remaining closed.

If, after the parts are set as shown in Figure 4 and the` pilot burner is lighted to hold the parts in the positions shown in this ligure, thel Pilot flame isv extinguished, the armature 4l is released. The spring 64 then moves the armature 43 to retracted position, and therstem 4l, by engagement with the pin 33, moves the pin 63 to the left, as the device is shown in Figure 4, relativ'e to the plunger 3i until the abutment 15 engages the plunger. This separates the contact 65 from the contacts B4, thus opening the circuit 22 and closing the valve I4 to shut off the supply of fuel to the main burner. The continued movement of the armature stem 43 t'o the left as the device is shown in the drawing returns the plunger 6I and button 12 to the position shown in Figure 3. With the parts in this position the colored or marked band or portion A12' of the button 12 projects from the adjacent end of the body member and flange 30', indicating that the switch is open. When the parts are in the position shown in Figure 4, vthe colored or otherwise marked portion 12' of the button 12 is concealed,v

thus indicating that the armature is held in attracted position and that the switch is closed.

The embodiment of the invention shown in the drawing is for illustrative purposes only, and it is to be expressly understood that the drawing and the accompanying specification are not to be construed as a definition of the limits or scope of the invention, reference being had to the appended claims forthat purpose.

I claim:

1. In e device of the class described, in combxnation, a rectilinearly movable insulating plunger, a coaxial pin carried by and slidable axially in said plunger, an abutment on said pin for cooperation with said plunger whereby the pin is moved with the plunger in one direction, said plunger having movement in the opposite direction relative to said pin, and cooperating contact means on said plunger and said pin for movement into closed circuit cooperation by relative movement between said plunger and said pin.

2. A device according to claim 1 wherein the insulating plunger is of hollow form and the cooperating contact means is disposed within the hollow interior of said plunger. I

3. In a control device of the class described, in`

combination, an electromagnet, an armature stem movable axially in opposite directions, an armature carried by said stem for movement to attracted position relative to said electromagnet by movement of said stem in one direction and to retracted position by movement of said stem in the opposite direction, an axially movable plunger coaxial with said armature stem and having an end wall, an actuating pin mounted for axial sliding movement in the end wall of said plunger at the axis thereof.said pin abutting endwise with said armature stern on one side of the end wall of the plunger and having an abutment between its ends for cooperation with said plunger whereby axial movement of said plunger in one direction moves the actuating pin axially therewith and said armature to attracted position by the abutment of said actuating pin with said armature stem, said plunger having axial movement in the opposite direction relative to said actuating pin when the amature is held in attracted position and the plunger isreleased, and first and second contact means on the opposite side of the end wall of the plunger, said second contact means being maintained in open circuit relation separated from said first contact means upon movement of said actuating pin with said plunger in moving said armature to attracted position and mov into closed circuit relation engaging said nrst contact means by movement o! said plunger in the opposite direction relative to said actuating pin with said armature held in attracted position by said electromagnet.

4. A-control device according to claim 3. wherein the plunger is an insulating plunger oi hollow form and said ilrst and second contact means are disposed within the hollow interior of said plunger.

5. A control device according to claim 3, wherein the plunger is an insulating plunger, with said ilrst contact vmeans carried by said insulating plunger and wherein said second contact means is carried by said actuating pin ior movement to open circuit relation separated from said iirst contact means by movement of said actuating pin axially relative to said plunger in a direction opposite the direction for moving said armature to plunger and said second contact means carried by said actuating pin for movement to open l:ircuit relation separated from said ilrst contact means by movement of said actuating pin axially relative to said plunger in a direction opposite the direction for moving said armature to attracted position.

7. A control device according to claim 3, wherein the end oi the actuating pin inwardly of said plunger has a rounded head and the adjacent end of the armature stem has an abutment member provided with a socket for cooperation with the rounded head of said actuating pin.

8. A control device according to claim 3, wherein the plunger is an insulating plunger, with said ilrst contact means carried by said insulating plunger and wherein said second contact means is carried by said actuating pin i'or movement to open circuit relation separated from said iirst contact means by movement of said actuating pin axially relative to said plunger in a direction opposite the direction for movingsaid armature to attracted position; and a spring interposed between a wall of said plunger and said second contact means and operable to move the plunger axially relative to said actuating pin and in a direction opposite the direction for moving saidl armature to attracted positionrwhen the armature is heldin attracted position by the electromagnet and the plunger is released whereby to move said second contact means into engagement with said ilrst contact means.

9. In a control device or the class described, in combination. an electromagnet, an amature movable rectilinearly to attracted position in which it is adapted to be held by said electromagnet and rectilinearly to retracted position. an actuator member movable rectilinearly in one direction to move said armature to attracted position and movable rectilinearly in the opposite direction. a coaxial insulating plunger member movable rectilinearly between said actuator member and said armature, a coaxial pin member slidable axially in said plunger member, a pair of contacts carried by one oi' said plunger and pin members. a cooperating contact carried by the other of said plunger and pin members. a rectilinearly movable armature stem coaxial with said pin and said amature and interposed therebetween. an adjacent abutment member having an opening through which said actuator member operates, and a coiled spring interposed between the plunger member and said abutment member and operating to hold the actuator member and plunger member against dropping from place when the device is positioned vertically with the actuator member directed upwardly.

A LEROY A. MATSON.

REFERENCES CITED The following references are of record in the ille of this patent:

l UNITED STATES PATENTS Number 

